The maximum values of rotation and displacement were modest (roll = 0.18°, pitch = 1.28°, yaw = 0.35°, superior = 0.80 mm, left = 0.24 mm, posterior = 0.39 mm). Spearman rank-order correlations demonstrated that FH density was not related to bulk motion in any direction (ps > 0.20), but FH density was related to task-correlated motion in the roll (i.e., ear-to-shoulder) and yaw (i.e., nodding) rotations (β = 0.27, p = 0.03; β = 0.28, p = 0.02, respectively).
